Gamma alumina promoted paraffin alkylation process



1961 R. GILBERT ETI'AL 2,971, 37

GAMMA ALUMINA PROMOTED PARAFFIN ALKYLATION PROCESS Filed Dec. 1, 1958PPROMOTER LIGHTER I l HYDROCARBON II A '43 ||G- is c 1 I 6b I2 [5 /2| rAIEIr PICKUP) I R\EACT|QN VESSEL ZONE INITIAL -SEPARATION ZONE PRODUCT mSEPARATION ZONE HIGHER PARAFFIN |5J/ HYDROCARB0N FEED GeZrggRMGI'gerf kJan c arm/c A/an Schr/es/w/m lNVE/VTORS ATTORNEY United StatesPater-11:0 F

2 I GAMlVIA ALUMINA PROMOTED PARAFFIN ALKYLATION PROCESS George R.Gilbert, Elizabeth, John E. McCormick, Ro- .;sell,e Park, and AlanSchriesheim,,Fords, N.J., assignors j Esso Research and EngineeringCompany, a corporation of Delaware Filed Dec. 1, 1958, Ser. No. 717,3136 Claims. c1. 260-68353) support comprising gamma alumina, underconditions that result in high yields of branched chain parafiinhydrocarbons of from 5 to 7 carbon atoms.

Petroleum, refiners are continuously faced with the problem of supplyingbetter and greater quantities of high octane rating motor fuels to meetthe requirements of modern high compression internal combustion enginesemployed in the automotive industry. Heretofore, the lsupplyof highoctane rating gasoline components has been augmented principally bypolymerization and alkylation processes using C and C petroleumfractions as Ljstarting materials. These processes have a numberdisadvantages in that they require severalseparate operations andnecessitate the use ofolefin hydrocarbons which are usually inrelatively limited supply. It has now been found that, by the use of apromoted aluminum bromidecatalyst, butanes and/ or pentanes can ,be.reacted directly with higher paraifin hydrocarbons to give good yieldsof C to C branched chain hydrocarbons v of high octane rating, providedcertain specific conditions are employed. It has previously beenproposed to con-. duct reactions of this type. but yields have been low,,freaction rates have been uneconomic and satisfactory productdistribution has not been obtained.

.In..accordance with the present invention, a paraffin hydrocarbon ,offrom 6 to 18 .carbon atoms is reacted with alarge excess of a butane ora pentane, preferably isobutane, employing as a catalyst AlBr supportedon or associated with gamma almuina, at. temperatures in the range offrom about 30 to about 140 F. and at pres- ,'sures sufiicient to keepthereacting hydrocarbons in the j. liquid phase. The products of thereaction are saturated l branched chain parafiin hydrocarbonspredominantly in .the C to C range. The preferredtemperature range isfrom about 50". to about 120 F.

.The nature and objectsof this invention and the man- ,ner in which theinvention can be practiced will be more 'readily understood whenreference is made to the ac- "-corhpanying drawings in which the singlefigure is a schematic flow planof'one process for practicing theiuventiom' r The process will bedescribed with-particular reference2,971,037 Patented Feb. 7, 1961 to the use of isobutane as the lightercomponent. Referring to the drawing in detail, a suitable butane feedstream containing at least initially a major proportion of isobutane isobtained by means of line 11 from a suitable source. A portion of thestream is conducted via line 11a through an aluminum bromide pick-upvessel 12 to dissolve aluminum bromide in a portion of the stream thatis conducted to the reaction zone. The remainder of the feed stream iscombined with the efiluent leaving the pick-up vessel via line 13 and isconducted into a react-ion zone 15. The latter zone contains one or morebeds of gamma alumina saturated with aluminum bromide.

A stream of ahigher parafiin hydrocarbon, as for example, heptane,octane, dodecane or cetane, or of mixtures containing the higherparafiins, is conducted into The reaction product leaves the reactionzone through line 18 and is conducted into an initial separation zone 20wherein light materials, including unreacted isobutane and normal butaneare removed overhead and recycled -to the reaction zone by means ofline'21. Hydrogen bromide, which is preferably present, will also berecycled via line 21. The heavier material, including C hydrocarbons andhigher, is conducted by means of line 22 into a product separation zone24 wherein C to C hydrocarbons are removed overhead by means of line 25While heavier material comprising C hydrocarbons and higher as well asany aluminum bromide that has been removed from the reaction zone isrecycled to the reaction zone by means of line 26. If desired,conditions can be adjusted in separation zone 24 to include normalheptane in the heavier material recycled through line 26, whileincluding the C branched chain isomers in overhead line 25.

In place of isobutane the feed in line 11 may comprise normal butane, inwhich case no higher hydrocarbon feed stock will be sent initially tothe reaction zonebut the butane will be recycled through line 18, zone20 and line 21 until a considerable amount of the butane has beenisomerized to isobutane. The process may then continue in the manneralready described, the recycle f isobutane being suificient to make thedesired reaction distribution of the products may be obtained. Forexample, at temperatures above about 'F. considerable cracking occursand the principal products are propane and lighter materials. Also ithas been established th at aluminum bromide alone or even in thepresence of 'conventional hydrogen halide promoters such as hydrogenbromide, in the absence of the support, is very much less active thanthe catalyst system of the present invention. Furthermore in order forthe reaction to proceed-satisfactorily it is necessary that sulficientaluminumbr'dmide be present not only to saturatethe support under thereaction conditions employed but also to leave at least a small amountdissolved in the react ng hydrocarbons.

A mixed catalyst in which a portion of the aluminum of line 17 and isrecycled to the reactionzone along with unreacted-butanes by means:ofline 21.

Although the process as described in'conjunction with the drawingCOHtGIIlPlfitEStdOWHflOW of the stream=through the catalyst bed, whichis preferred, upfiow can also be used. Also in place of a fixed bedprocess,a moving bed "of catalyst could be used. Alternatively, a slurrytype of operation could be employed wherein a suspension of .catalystis'maintained in the reacting hydrocarbons, the .slurrybeing stirred in:the reactor with suitable mechanical stirring means or recirculatedthrough the reactor by pumping means. Where slurry operation is used,the

slurry is removed from the reactor at the .end of the reaction period,inthe case of batch operation, or as a fraction of the circulatingstream in the case of continuous operation, and sent to suitableseparation equipment to separate the catalyst :from the .hydrocrabons.separation equipment may comprise a simple settling tank, .a centrifuge,or a filter, for example, or :suitable com- The binations of such means.

It is preferred that the minimum mol ratio of isobutane and/orisopentane to higher parafiin be about :3 to 1 but should preferablybeno higher than about 1-2 to .1. If sufiicient iso-C is not present inthe reaction zone to effect alkylation of the materials obtained whenahigher -paraflin or other higher product of the reaction is cracked bythe catalyst catalyst sludging will result. The feed stock must beessentially free of aromatic hydrocarbons and not more than about 0.02%of such material should be present. An added advantage of the catalystsof the present invention is that naphthene hydrocarbons may be toleratedin the feed stock up to about volume percent.

With increased naphthene content the reaction severity must be increasedsomewhat --as compared to 'a-reaction in the absence of naphthenes.

This may be accomplished by raising the temperature and/or lowering thefeed rate, for example.

Feed rates may vary from about 0.3 to about 2 v./hr./v.

. (liquid volume of total feed per hour per volume .of total catalystplus support) the higher feed rates being preferred .whenlittle or nonaphthenes are present.

To remove aromaticsfrom the .feed stock conventional techniques may beemployedsuch as solvent extraction,

. hydrogenatiomacid treating and thelike, .as well as treatment withselective adsorbents such as molecular sieve .zeolites. It isnotnecessary that the. higher hydrocarbons used be individualhydrocarbons such as heptane or octane or cetane, for example, butmixtures may be used, such as a petroleum fraction containing paraffinichydrocarbons in the range of .6 to 18 carbon atoms. Although, as stated,hexane is one of the higher hydrocarbons that may .beused, it .ispreferred to employ heptane or higher. Essentially thesame productdistribution is obtained-with hexane 'as withheptane but the reactionrate is lower by a factor of about 3.

Other sources of the higher parafiin hydrocarbons for the reactioninclude light virgin naphthas, and paraffin rafiinates from-theextraction of .hydroformed petroleum fractions.

.-At the start of the process the gamma alumina may be :saturated withaluminum bromide and then placed in the reaction zone, or,alternatively, the gamma alumina alone may be placed in the reactionzone and then satu- "rated :with aluminum bromide carried in with aportion rot'lthefeed. Another method of preparation is to mixconsiderable yields of C and C isomers.

the aluminum halide with the support and to hear the mixture to effectimpregnation. If desired, loosely held aluminum halide may be removedfrom the catalyst mass by heating the mass and passing through it a gassuch as carbon dioxide, methane, hydrogen or nitrogen.

Alternatively the support may be impregnated by dissolving the aluminumhalide in a suitable solvent such as ethylene dichloride or dioxane, forexample, and the porous carrier impregnated with this solution, followedby heating to remove the solvent and loosely held aluminum halide. Stillanother alternative is to employ a powdered support or promoter, ,mixthe aluminum halide with it, and compress the mixture into pellets.

The following 'examples'serve to illustrate-the practice of the presentinvention.

EXAMPLB'I Comparative tests were made with'var'ious catalyst systems asshown in Table I. In each instance amixture of 160 cc. (90.5 grams) ofisobutane and 40 cc. (27.5 grams) of a normal heptane feed, whichconsisted of of normal heptaneand 5% of methyl cyclohexane,

was stirred for 3 hours at 72 F. with one of the catalyst systemsmentioned above. At the end of each run tion of the product consisted ofC hydrocarbon isomers. On the other hand, gamma alumina was a veryeffective promoter for the aluminum bromide catalyst and gave Still,greater activity was obtained when -.a small proportion of .hydrogenbromide was employed in addition to the gamma alumina.

The gamma aluminadlsed in these tests was prepared as follows. Aluminumalcoholate was prepared .by reaction of aluminum metal with a 3 to 1volume ;ratio mixture of mixed amyl alcohols and heavy virgin naphtha,using a trace of mercuric chloride to promote the reaction. The ratio ofreactants was about.3 pounds .of aluminum per 7 gallons of thealcohol-naphtha mixture. The aluminum contentof resulting aluminumalcoholate solution was about 94 to 97 grams of alumina per .liter. Thealuminumalcoholate was pump-mixed atroom temperature with a diluent (22volumes of alcoholate per volume of diluent) consisting of mixed amylalcohols, heavy naphtha and acetic acid in a volumetric ratio of 15 to15 to 1. This stream was then hydrolyzed with 6.8 volumes of water atroom temperature in a-second mixing pump. The mixed product was pumpedthrough .a heat exchanger held at F. outlet temperature.

From the heatexchanger the product went to a separator held at 160 F.The alcohol and solvent layer were continuously withdrawn from the topof the separator while the aqueous layer flowed continuously into asteam jacketed stainless steel sol cooking unit and heated to boiling.for 4 hours. During the heating, alcohol and solvent remaining in theslurry were taken overhead from the cooking unit, together with water.The alcoholsolvent mixture and water were separated and measured, andthewater returned to hold constant volume.

Five [GO-gallon batches of alumina sol were prepared in this .manner andmixed together. Analysis .after mixing indicated an alumina content of3.1 percent. The entire mixture was spray dried in a tower in a risingstream of flue gas having anentering temperature .of 590-625 F. and anexit temperature of 220-230 F., the entering stream of alumina sol beingpreheated to F. The 500 gallonsof aluminasol were dried in seven hoursto produce 161 pounds of spray dried product containing 32% volatilematter. .About.5'l0 pounds of water were evaporated ,per hour during.this drying operation. The product obtained was gammaalumina. Beforeusing :it as a support or promoter for .aluminum 5 bromide in the't'estsdescribed herein it wasflc'alcined -at 1100 F. for 4hours. I Y Table ITest 1 Test 2 Test 3 Test 4 Catalyst, grams:

AlBri 23. 6 23. 6 23. 6 23. 6 Gamma Alumina 42. 7 42.7 EB: 24 1. 1

Analysis oi Product, Weight 1 Percent:

ISO-C5 0. 4 0. 5 37. 4 41. 8 11-0 0.3 as 5.3 g 6.7

Total 06 0.7 4.1 42.1 48.5

T0151 Ca 0. 5 0. 3 22. 0 24. 1

Total C1 98. 8 95. 6 32. 7 24. 9

EXAMPLE 2 In a manner similar to that employed in Example 1, comparativetests were made with gamma alumina, eta alumina and calcined bauxite.Each of these materials 'was employed with aluminum bromide in 2different ratios of catalyst to support. The same reaction temperatureand time and the same hydrocarbon feed was employed as in Example 1. Thegamma alumina was prepared in the manner previously described. The etaalumina and the bauxite were obtained from commercial sources. In eachcase the support used was calcined for 4 hours at 1100 F. before use. Itwill be seen from the data presented in Table II that gamma alumina wasmuch more active than either of the other two supports in converting theisobutane and normal heptane into C and C paraffin hydrocarbon isomers.

Gamma alumina prepared from sodium aluminate and obtained commerciallyshowed about the same activity as that reported in Table II. In asimilar test, the commercial gamma alumina in the ratio of 47.2 grams to23.6 grams of AlBr gave, in the 3-hour test, 42.4% C hydrocarbons, 26.0%C hydrocarbons and 30.7% C hydrocarbons.

Table II Promoter Gamma calcined Eta Alumina Bauxite Alumina Promoter,grams 47.2 47.2 47.2 47.2 47.2 47.2

AlBl'a, grams 23.6 35.3 23.6 37.8 23.6 35.4

Analysis of Cr+ Product,

Weight Percent:

EXAMPLE 3 Even greater activity for the desired alkylation reaction wasobtained, as measured by conversion of C hydrocarbons to C and Chydrocarbons, by using larger ratios of aluminum bromide to gammaalumina. The test results are shown in Table III. Again the samereaction temperature and time and the same hydrocarbon ilhersamm aluminawas prepared as described above.

Table 11 v Gamma Alumina, grams 1 47.2 1 i 45.2 AlBra,grams 47.2 47.2 iHBr,g|-am-z i a I .0 I. 0 7..

Analysis of 0 Product, Wei ht Percent" iso-Cs 48.0 --48.6

. 8.0 7.0 se a 55.6 28. 6 29.4 1.:3 1.s

It has been established in other studies that in order for the reactionto proceed satisfactorily it is necessary to have present in thereaction zone sufficient aluminum bromide so that not only will thetotal adsorption capacity of the gamma alumina be satisfied but somealuminum bromide will be present in solution in the reactinghydrocarbons. To make sure that such a condition will exist incontinuous operation, the gamma alumina in the reaction zone should besaturated with aluminum bromide, and sufiicient aluminum bromide shouldbe dissolved in at least one of the entering streams of reactinghydrocarbons so that a minimum of 0.1 weight percent of aluminum bromidebased on feed is sent to the reaction zone.

Although in the illustrative examples given, the higher parafiinhydrocarbon reactant comprised heptane, other studies have shown thatwith hydrocarbons of greater molecular weight such as octane, cetane, oroctadecane, the product distribution is essentially the same as withheptane.

Certain modifications of the process outlined hereinbefore will occur tothose skilled in the ant. Such modifications are contemplated within thescope of the pres-' ent invention. For example, if the yield of Chydrocarbons is larger in proportion to the C hydrocarbons than isdesired, the product may be distilled to separate a C cut which may thenbe used in a conventional alkylation step with an olefin. such asethylene, propylene or a butene, employing the usual alkylationcatalysts such as sulfuric acid, phosphoric acid, hydrogen fluoride, oran aluminum halide. Alternatively, the C out can be sent to a secondreaction zone of the type herein described for reaction with highernormal parafiin hydrocarbons.

It is to be understood that this invention is not to be limited to thespecific embodiments and examples herein described and presented butthat its scope is to be determined solely by the claims appended hereto.

What is claimed is:

1. A process for the preparation of high octane naphtha componentsconsisting largely of branched chain paraffin hydrocarbons of 5 to 7carbon atoms which comprises reacting a minor proportion of a straightchain parafiin hydrocarbon of from 6 to 18 carbon atoms with a majorproportion of a lighter hydrocarbon selected from the group consistingof butanes and pentanes, at temperatures no higher than about F., in areaction zone in the presence of a catalyst comprising aluminum bromideand gamma alumina and maintaining in the reaction zone sufiicientaluminum bromide to furnish aluminum bromide in solution in the reactinghydrocarbons in addition to the quantity required to satisfy the totaladsorption capacity of the gamma alumina.

' 2. Process as defined by claim 1 whe-reinfrom about 0.1 to about 8percent of hydrogen bromide, based on .7 he *re'acting hydrocarbons,:present in :the reactio'n zone.

3. Process as definedrby claim 1 wherein the mol ratio ,of vsaid lighterhydrocarbon selected from the group consisting of butanes and pentanesto said hydrocarbon 10f from 6 to l8pcai'bonatoms in the reactionzone'isin :the range ofifrom about? -to 1 -to-about 1210 :1.

4. Process as defined by claim 11 wherein naphthenic hydrocarbons :arepresent in-said reaction zone.

' 5. -Process as defined by claim '1 'wherein the temperature "of ;the"reaction is in the range of about 50 10 about 5120 6. Process asdefined by claim 1 wherein reacting hydrocarbons are continuouslyconducted into said reaction zone and reaction products are continuouslyre- 15 References Citedin the file of this patent UNITED STATES PATENTS2,349,458 Owen i.. May 23, 1944 2,370,144 Burk Feb. 27; 19,145 2,401,925Gorin June -11, 1 946 2,41'5; 06'1 De Simoet al. Jan. 28, 1947 ML. A

1. A PROCESS FOR THE PREPARATION OF HIGH OCTANE NAPHTHA COMPONENTSCONSISTING LARGELY OF BRANCHED CHAIN PARAFFIN HYDROCARBONS OF 5 TO 7CARBON ATOMS WHICH COMPRISES REACTING A MONOR PROPORTION OF A STRAIGHTCHAIN PARAFFIN HYDROCARBON OF FROM 6 TO 18 CARBON ATOMS WITH A MAJORPROPORTION OF A LIGHTER HYDROCARBON SELECTED FROM THE GROUP CONSISTINGOF BUSTANES AND PENTANES, AT TEMPERATURES NO HIGHER THAN ABOUT 140*F. INA REACTION ZONE IN THE PRESENCE OF A CATALYST COMPRISING ALUMINUMBROMIDE AND GAMMA ALUMINA AND MAINTAINING IN THE REACTION ZONESUFFICIENT ALUMINUM BROMIDE TO FURNISH ALUMINUM BROMIDE IN SOLUTION INTHE REACTING HY-